One might argue that he should have been more aggressive in purchasing other IP portfolios - maybe Nortel (although that may have been before he was at Google) and Sun of course.
But Motorola gave Google exactly what it needed - a mature patent portfolio which other companies would have to cross license.
The Nortel patent portfolio sold for $4.5 billion, which was higher than Google was willing to pay.
Andy Rubin did not like what Samsung was doing with Android and wanted a captive OEM. This doubled Google's headcount, it changed Google's financial numbers materially, it cost a fuckton of money even at Google scale at a time when it was apparent that no phone OEMs were very profitable, and it was strategically incoherent.
Andy Rubin was exactly the right guy to make Android a success. But buying Motorola and intending to keep it as a captive OEM was a large mistake.
I found this via a WSJ article from 2014:
> Mr. Rubin is an entrepreneurial spirit who likes to run his own show and was facing constraints on his activities at Google, a person familiar with the executive and Google said. A Google spokesman declined to comment on why Mr. Rubin left.
> “It’s surprising and sounds pretty unplanned,” said Scott Strawn, an analyst at research firm IDC. “If it was voluntary on Mr. Rubin’s part, you would think he would see part of the robotics project through to completion to have something to show publicly before leaving.”